1. Field of the Invention
The present invention relates to a paper sheet processing apparatus and an image forming system.
2. Description of Related Art
Conventionally, as a post-processing apparatus for performing various types of post-processing on a plurality of paper sheets conveyed out from an image forming apparatus or the like, there is known a paper sheet processing apparatus in which a required number of paper sheets are stacked and matched and then, which performs binding processing by driving binding pins in the matched paper sheets.
In such paper sheet processing apparatus, there is provided a technique which perform an accurate biding processing by a hold-down member supporting the paper sheets which are stacked and aligned by pressing the paper sheets in their thickness direction (for example, see Japanese Laid-open Patent Application 2004-284767).
However, even when a bundle of paper sheets is held down by a hold-down member as in the above mentioned conventional paper sheet processing apparatus, there are cases where the paper sheet on the top of the bundle bulges in the thickness direction of the bundle of paper sheets. For example, when the binding pins 201 and 202 are driven in at predetermined two positions in the bundle of paper sheets SA1, respectively, in a state where the paper is bulged as shown in FIG. 9, a good appearance cannot be obtained because the bulged portion remains in the bundle of paper sheets SA1 between the binding pins 201 and 202.